Fuel supply system for continuous combustion turbine type aircraft



Nov. 21, 1950 F. H. CAREY 2,530,649

FUEL SUPPLY SYSTEM FOR CONTINUOUS comaus'rxon TURBINE TYPE AIRCRAFTFiled Jan. 14, 1948 4 Sheets-Sheet l linen rag 67/. Gaefif arw w Nov.21, 1950 F. H. CAREY 2,530,649 a FUEL SUPPLY SYSTEM FOR CONTINUOUScomausnou TURBINE TYPE AIRCRAFT Filed Jan. 14, 1948 4 Sheets-Sheet 2 Y,a 2 M N M i P WC Yw y H. F 4 Y/ a Nov. 21, 1950 F H CAREY I 2,530,649

FUEL SUPPLY SYSTEM F OR CONTINUOUS COMBUSTION TURBINE TYPE AIRCRAFTFiled Jan. 14, 1948 4 Sheets-Sheet 3 a/YW W Nov. 21, 1950 F. H. CAREYFUEL SUPPLY SYSTEM FOR CONTINUOUS COMBUSTION TURBINE TYPE AIRCRAFT FiledJan. 14, 1948 4 Sheets-Sheet 4 Patented Nov. 21, 1950 FUEL SUPPL YSYSTEM: FOR," CONTINUOUS COMBUSTION TURBINE TYPE AIRCRAFT FrederickHenry Carey, Cheltenham, England, assignor to Dowty Equipment Limited,Cheltenham, England Application January 14, 1948, Serial No. 2,341 InGreat Britain December 24, 194'? Claims. (Cl. 158-36-4) This inventionrelates to systems for supplying liquid fuel to the engine of acontinuous combustion turbine type power unit, such as is shown in mycopending application, Serial No. 2,343, filed January 14, 1948, and isconcerned with the problem of leaving the engine burners and combustionchambers dry in order that a fresh starting-up operation can be carriedout with safety and without detrimental effects upon the engine. To thisend, and in accordance with the invention, such a system comprises pumpmeans which, during a stopping condition of the system; serves as ascavenging pump by having its inlet in communication with the burnersand its outlet in communication with the tank. It is convenient to useas the scavenging pump a pump which during starting or runningconditions of the engine forms a part of the normal supply system byserving or assisting in the delivery of fuel to the burners. When such apump is enginedriven it is utilized as a scavenging pump in accordancewith the invention by transferring the supply communication with theburners from the outlet to the inlet of the pump and at the same timeplacing the outlet'of the pump in communication with the tank. In thisway flow in the supply line from the pump to the burners is reversed andany fuel which is not consumed at the burner nozzles during the processof stopping the engine and any fuel in the system which is adjacent tothe burners will be withdrawn by the pump and passed back towards thefuel tank.

The necessary modifications to the system to efiect changeover fromrunning to stopping can conveniently be made by one or more valves,turn-cocks, or equivalent, operated simultaneously by a hand or otheractuator.

By means of the invention, the burners and adjacent portions of thesystem are automatically drained of fuel thus avoiding the risk of fuelpools forming in the combustion chambers which on starting would causelocal and" general overheating of the engine. It is an advantage of theinvention therefore that there is no necessity for draining away ordumping unused fuel which hitherto would have succeeded in entering andforming pools in the combustion chambers.

It is not essential that the whole of the system be drained in this way,it being sufllcient and in fact desirable to drain only the burners andthe fuel lines in the vicinity of the burners, and to maintain anymovable parts of the system, such as pumps and valve elements, in aflooded condition to avoid the risk of corrosion.

The invention is applicable to systems of differing types and someexamples will now be described with reference to the accompanyingdiagrammatic drawings, of which:

Figures 1 and 2 show one system in its normal 7 running and stoppingconditions respectively, and

Figures 3 and 4 are similar views of another system.

The system shown in Figures 1 and 2 incorporates simple direct-injectiontype burners one of which is designated by the reference numeral I. Theburners i aresupplied with fuel from a tank 2 by an engine-driven pump 3which draws the fuel along a conduit 4, through a portion of what may betermed a change-over valve indicated generally at 5, and along an intakeconduit 6, and delivers it along the output conduit 1 through a meteringvalve 8, along the conduit 9, and through another part of thechange-over valve 5 to the supply line ill of the burners. When thesystem is to be converted from its normal running to its stoppingcondition the movable element of the change-over valve 5 is displaced bythe clockwise rocking of a control lever II from the position shown infull lines in Figure 1 to the position shown in full lines in Figure 2.This displaces the movable elementof the valve 5 so that the intakeconduit 6 of the pump 3 is cut off from the conduit 4 and is placed incommunication with the supply line ID of the burners. Flow in the supplyline I0 is therefore reversed, and the pump delivers through the conduit1 and branch conduit I2 and through a section of the change-over valve 5to the conduit 4 by way of the branch conduit l3. At the same time thedelivery conduit 9 is cut off from the normal supply line ID, at thevalve 5, hence the line 9 does not drain. Reversal of the metering valve8,

normally simultaneously with reversal of the valve 5, furtherprevent's'drainage of the line 9.

The system shown in Figures 3 and 4 incorporates burners of the knownspill type one of which is indlcated at I4, and comprises essentiallytwo pumps of which one, an engine-driven circulating pump l5, operatesnormally to circulate fuel around a circuit including a supply conduit16, Ilia, a burner ring l'l, burners ll, of which several would beconnected to the burner ring I1, and a collector ring l8 and returnconduit I9.

The other pump, an engine-driven supply pump.

20, operates normally to inject fuel into the circulating flow at apoint in the return conduit IS. The supply pump 20 withdraws fuel from atank 2|, the fuel flowing along a conduit 22, through a section of achange-over valve 23 and along an intake conduit 24. The pump deliversthe fuel along a conduit 25, through a metering valve or throttle 26,along a conduit 21, through another section of the valve 23 and along aconduit 28 which joins the return conduit l9 running from the collectorring I. to the circulating pump l5. When the system is to be transformedfrom its normal running condition shown in Figure 3 to its stoppingcondition shown in Figure 4, a hand lever 29 associated with the movableelement of the valve 23 is moved in a clockwise direction away from thefull line position of Figure 3 into the full line position of Figure 4.The communications between various conduits is now modifled with theresult that a portion of the burner supply line It, indicated at 16a,now communicates through a portion of the valve 23 and through a conduitwith the return conduit [9 so that fuel within the burners I4 and withinthe burner and collector rings l1 and I8 respectively is withdrawn alongthe return conduit I8 by the pump l5 which now delivers through theconduit l6 and through a section of the changeover valve 23 back to thetank 2| along the conduit 22. The circuit is at the same time modifledso that the supply pump 20 now serves merely to circulate fuel around acircuit including the conduit 25, the change-over valve 23, and theconduit 24. In case the system should be changed to a stopping conditionwith the metering valve 26 open, the flow along the conduits 21 and 28by which the fuel normally injects into the circulating flow, isinterrupted by the change-over valve 23.

In the examples illustrated, the flow in the supply line from the pumpto the burners is reversed and any fuel not consumed at the burnersduring the stopping process and any fuel adjacent to the burners iswithdrawn back towards the tank so that no fuel is allowed to form poolsin the combustion chambers of the engine. The invention enables a freshstarting-up operation to be carried out with safety and withoutdetrimental effects upon the engine and avoids the necessity for the"dumping of any fuel.

I claim:

1. A fuel supply system for aircraft engines of the continuouscombustion turbine type, comprising a fuel reservoir, a burner nozzle,pump means, a change-over valve casing, a valve in said casing shiftablebetween a normal operating position and a stopping position, and conduitmeans interconnecting the pump means with thereservoir and with theburner nozzle, respectively, by way of the valve casing, for supply offuel during normal operation to the nozzle and return of unused fueltherefrom during stopping, said conduit means including two by-passpassages, one between the nozzle and the intake side of the pump meansand the other between the delivery side of the pump means and thereservoir, respectively, and said valve being formed with lands andpassages arranged to close off said by-pass passages during normaloperation and leave open the normal pump supply and delivery conduits,but to open the by-pass passages and close off the normal pump supplyand delivery conduits, for withdrawing from the nozzle during stoppingthe unused fuel which was theretofore supplied to it during normaloperation, and for returning the so-withdrawn fuel to the fuelreservoir.

2. A fuel supply system as in claim 1, characterized in that the burnernozzle is formed for supply of fuel to it and return from it of unusedfuel, and further characterized in that the pump means comprises acirculating pump and a leperate supply pump, and wherein the conduitmeans directly connected to the circulating pump normally affords aclosed circulating path which includes the burner nozzle and its supplyand return lines but not the reservoir, and the com duit means directlyconnected to the supply pump draws from the reservoir and feeds into theburner return line to the circulating pump, and further characterized inthat the by-pass passages are arranged to provide a closed circulationpath for the supply pump during stopping, and to connect th burnernozzle to the intake side of the circulating pump and the lattersdelivery side to the reservoir.

3. A fuel supply system as in claim 1, characterized in that the burnernozzle is formed for supply of fuel to it and return from it of unusedfuel, and further characterized in the inclusion of conduit means toconnect the supply and return sides of the nozzle to the intake side ofthe pump means during stopping, but to connect them respectively to thedelivery and the intake sides during normal operation.

4. A fuel system for an aircraft internal combustion turbine enginecomprising. in combination with a burner, a fuel tank, and a pump; firstconduit means extending from the fuel tank and branched for connectionwith each of the intake and delivery sides of the pump, second conduitmeans extending from the burner supply port and likewise branched forconnection with each of the intake and delivery sides of the pump; valvemeans in said first and second conduit means controlling communicationbetween the pump and each of the fuel tank and the burner, and normallypositioned to leave open one branch in the'first conduit means forsupply from the fuel tank to the intake side of the pump, and toblockthat branch from the fuel tank to the delivery side of the pump,and also to leave open one branch in the second conduit means for supplyfrom the pump to the intake port of the burner, and to block that branchfrom the intake port of the burner intake port to the intake side of thepump, said valve means being shiftable to a stopping position, whereinto open that branch in the second conduit means which establishescommunication between the burners intake port and the intake side of thepump, and to block that branch which formerly established communicationbetween the burner and the delivery side of the pump, and also to openthat branch in the first conduit means which establishes communicationbetween the delivery side of the pump and the fuel tank, and to blockthat branch which formerly established communication between the fueltank and the intake side of the pump.

5. A fuel supply system for aircraft engines of the continuouscombustion turbine type, comprising a fuel reservoir, a burner nozzle, asingle pump, a change-over valve casing, a fuel supply line running fornormal operation to the pump from the reservoir by way of said valvecasing, and having a branch normally blocked off, for alternate returncommunication from the valve casing back to the reservoir, a fueldelivery line running from normal communication from the pump, by way ofthe valve casing, to the burner nozzle, and having a branch, normallyblocked off, for alternate return communication from the pump to thevalve casing and thence by way of theaforesaid alternate branch to thereservoir, and an alternate 5 by-pass, normally blocked oil, from thenozzle by way of the valve casing to the intake side of the pump, and avalve in said valve casin shiftable between a normal operating position,to afford communication between the reservoir and the pump, and thenceto the burner nozzle, and a a stopping position, wherein it blanks oilthe normal connections between the pump and reservoir and the valvecasing, and establishes the alternate connections, for pump-actuatedscavenging of the burner nozzle and return of unused fuel therefrom tothe reservoir.

FREDERICK HENRY CAREY.

6 REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,334,679 Mason et al Nov. 16,1943 2,494,778 Plass Jan. 17, 1950 FOREIGN PATENTS Number Country Date14,234-28 Australia July 4, 1929

